1. Field of the Invention
The present invention relates generally to a printing apparatus and a check pattern printing method. More specifically, the invention relates to a printing apparatus which can print a check pattern used for performing registration adjustment between a plurality of printing heads and for judging whether printing is performed normally, and to a printing method of printing the check pattern.
2. Description of the Related Art
An ink-jet printing apparatus as a typical printing apparatus, particularly a bubble-jet type printing apparatus has an advantage of arranging ink ejection openings of a printing head in high density and whereby of being capable of performing high precision printing. On the other hand, it is one of trends for a recent printing apparatus to require printing an image of high precision and high image quality.
Incidentally, in the apparatus employing a plurality of printing heads, such as an apparatus performing a full-color printing, it has been known to perform a registration adjustment so that respective dots formed by inks ejected from the printing heads can maintain predetermined positional relationship, for example, positional relationship in which dots formed by inks ejected from these printing heads are overlappingly formed at substantially the same position on a printing medium. One prior art for the registration adjustment is to perform printing a predetermined check pattern on the printing medium by respective heads and to adjust ejection timing of respective head on a basis of deviation amount of respective patterns with respect to each other.
Further, it has been performed that when inspection is performed for each ejection opening whether ink ejection is performed normally or not, by actually performing ink ejection to the printing medium, in similar manner, and by visually checking the results of printing.
However, in the apparatus performing high precision printing, when the foregoing conventional registration adjustment or checking on normal printing is to be performed, it may occur that the adjustment or the check may be insufficient.
More specifically, for performing high precision printing, the registration adjustment per se has to be performed in high resolution. For example, when the high precision printing of 1200 dpi compared to a normal printing of 400 dpi is performed in scanning direction of the printing head, the registration adjustment at three-times higher precision with respect to the registration adjustment for the normal printing is required. Therefore, a longer time is required for the registration adjustment depending upon increasing of the resolution.
On the other hand, the check pattern to be printed on the printing medium for adjustment of registration or checking of the normal printing is preferred to have no bleeding or the like for performing checking in high precision. Therefore, for example, with respect to the printing medium used for performing printing of the check pattern, it is required to use a relatively expensive printing medium which is difficult to cause bleeding. In this case, for example, when only a single check pattern is printed on one printing medium, a correspondingly increased number of printing medium has to be wasted to cause a relatively high running cost.